This invention relates to a tilting window comprising a sash mounted in a main frame by means of hinge devices inserted between the associated side members of the sash and the main frame, respectively.
In a known window of this type, disclosed e.g. in the specification of Norwegian Patent No. 122,614, the hinge devices each includes two arms of different lengths and extending parallel to each other in the closing position of the window, both arms of each hinge device at one end being pivotally connected to the main frame at a distance greater than the longitudinal difference of the arms, and at their other ends being pivotally connected with a third arm at points having a distance which is approximately equal to the distance of the connection points on the main frame reduced by the longitudinal difference of the two first mentioned arms. The window sash is mounted in the third arm by a pivot pin located adjacent the horizontal axis through the centre of gravity of the sash, and for the purpose of coordinating the movement of the sash during opening and closing of the window with the movement of the arms, the sash is provided at either side of the window with a pin extending parallel to the tilting axis of the sash and mounted at the upper end of its side member. Each pin is slidingly received in a guide groove provided in the side member of the main frame and extending approximately over the full length thereof. A suitable dimensioning of said arms ensures that the horizontal axis through the centre of gravity of the sash during opening and closing is displaced outwardly from and inwardly against the main frame while following a substantially horizontal path so as to avoid noticeable lifting and lowering movements of the sash, and the pin and groove connection between the sash and the main frame is simultaneously responsible for the tilting movement of the sash, as it causes any displacement of said axis to be accompanied by a corresponding angular or tilting motion of the sash.
In the manufacture of windows of this type it is easy to mill out the guide grooves in the side members of the main frame as a step in their processing prior to their being assembled to a complete frame, but it might be rather difficult to perform such a milling operation in a frame after it has been mounted in situ. There has not so far been any serious need in this respect, but such a demand arises increasingly along with renewal of windows with a view to reducing the loss of heat from a building. For instance, it may be actual to substitute a single layer of glass with two or even three layers; if so, it is evident that in most cases a considerable amount could be spared if, instead of renewing the whole window, it could do only to mount a new glass-supporting frame in an existing main frame which originally may have been intended for other types of sashes.
This is made possible in a simple manner through the present invention, the principles of which, however, are obviously applicable also for production of complete windows.